On Jan 30, 19:33, Tony Duell wrote:
> The names comes from the fact that if the film was perfect there's a
> reciprocal relationship between the exposure time and the aperture area
Exactly.
> In other words, bracket the exposures - take the same picture at several
> different exposures and use the best one.
> > The effect is that colour balance can be wildly different at very
short > > or very long exposure times.
> While undoubtedly true in theory, I don't think this will affect most
> people on this group. I've taken a lot of pictures inside buildings
> without flash (exposures of 20 seconds, perhaps), using Kodachrome.
Kodachrome is more tolerant than many films, but in general you'd need
exposures over a minute or so to see a serious cast develop.
> > Also, ordinary B/W film is "panchromatic" -- sensitive to most of the
> > visible colour range (and also to UV, which is why most professionals
tend
> > to put a UV or "skylight" filter on every lens as a matter of course).
>
> That, and a new filter is cheaper than a new lens if you happen to knock
> it against something ;-)
Or have it splattered with salt spray :-)
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
Received on Sat Jan 30 1999 - 16:30:23 GMT